I turn on the light and a whole supply chain is at work behind the pleasant light coming out of the bulb. How did the bulb get to my place? How about its filament? Where does the glass come from? Who assembled it? How does power get to it (A: the wires)? Where do the wires come from? Who installed the power lines? Also, the transformers that connect those wires to the power plant, where do they come from? The coils and the casings may be coming from multiple continents! And so on…